1. Technical Field
This invention relates to switch point assist devices for railroads and, more particularly, to a switch point roller assist apparatus for attachment to a railroad rail at a switching location which includes a main support structure, a rail securement clamp adjustably mounted on the main support structure, an elongated tie bar adjustably mounted on the main support structure and generally perpendicular thereto and a roller support cage on which at least one roller is rotatably mounted, the roller support cage pivotally mounted on the main support structure such that the rollers may be adjusted vertically relative to the main support structure.
2. Description of the Prior Art
Railroad switching devices usually comprise tapered metal blades or tongues which set alternative routes of running rails. The term "turnout" is also used to denote a curved track leading from one track to another which takes place at a switching point. The commonest form of switch is the split switch in which one rail of the main track and the outer rail of the turnout are continuous. The point rails are connected respectively to the second rail of the main track and the inner rail of the turnout. The switch operates in the following manner: when the point rail connected to the second rail of the main track is in contact with the outer rail of the turnout, a locomotive traveling on the main track will continue on the main track; when the point rail connected to the inner rail of the turnout is in contact with the first rail of the main track, a locomotive traveling on the main track will be switched over to the turnout. The point rails are spaced such that in no circumstances can both point rails be in contact with an adjacent rail of the main track or of the turnout. To secure the point rails in a particular spaced apart dimension, switch rods are provided extending between the point rails and mounted towards the tapered ends of each point rail.
To switch the point rails from contact with one rail of the main track to contact with the outer rail of the turnout and vice versa, both hand-operated and power-assisted switches are used. However, in both types of switches, the tapered ends of the point rails rest on a flat metal plate over which the ends of the point rails are slid. Clearly, if a power-assisted switch is being used, the amount of force needed to move the point rails is not critical, as the force is provided by hydraulics or the like. However, in a standard hand-operated switch, a large amount of force may be required to slide the point rails over the metal plate from contact with one rail to another due to the friction between the point rails and metal plate. The intense effort required to move the point rails thus may result in muscle strains or back injuries to the operator of the hand-operated switch. There is therefore a need for devices which will remove the point rails from contact with the metal plate while the point rails are being moved, yet return the point rails to contact with the metal plate upon being moved into correct position.
One well-known device for assisting movement of the point rails is the switch point assist roller manufactured by various companies. Such roller assist devices commonly include an extended C-channel main support section, a tie bar mounted generally perpendicular to the C-channel at one end of the C-channel, a clamping device for securing the opposite end of the C-channel to the outer flange of a rail and one or more rollers rotatably mounted in the C-channel generally perpendicular thereto. The rollers are intended to lift the point rail slightly above the metal plate such that the point rail may be slid across the rollers. However, one of the problems still encountered with the point rollers' other prior art is that a good deal of force must be applied to slide the point rail up onto the first roller, due to the fact that the first roller is above the level of the metal plate. Thus, while the total amount of force needed to move the point rails is lowered by the devices found in the prior art, the initial force which must be applied is often at least as great as would be encountered if no point roller assist device were present. It is widely known that brief periods of intense exertion cause most muscle sprains and back injuries, and the point roller assist devices of the prior art do not completely address and solve this problem.
Another problem encountered with those devices found in the prior art is that in many cases, switch locations are high-traffic areas. Therefore, irregularities in the ties and rails may be present at the location where the switch point assist apparatus is to be located. Various examples are found in the prior art which attempt to address irregular rails and ties, such as including a number of shims underneath the tie bar or other such methods. However, none of these methods can be employed once the switch point assist apparatus is in place on the rail. There is therefore a need for an adjustment means which can be adjusted to fit the various irregularities encountered on the rail bed after the switch point assist apparatus is installed on the rail.
A further disadvantage of the prior art is found in the clamp device which secures the switch point assist apparatus to the rail. One of the common problems encountered in prior art clamps is that the clamp plate which contacts the rail flange is frictionally secured to the flange but is not frictionally secured to the C-channel. This results in the clamp plate sliding off of the rail flange incrementally each time the main rail vibrates (i.e. when a locomotive runs over the track). Eventually, the clamp plate will either be dislodged from the rail flange, resulting in the switch point assist roller falling from the main rail, or require periodic repositioning to the original location of the plate. There is therefore a need for a clamp which will not slide off of the rail flange due to vibrations of the rail.
Therefore, an object of the present invention is to provide an improved switch point roller assist apparatus.
Another object of the present invention is to provide a switch point roller assist apparatus which includes an adjustable tie bar and adjustable height rollers in a roller support cage which is pivotally mounted to the main support structure.
Another object of the present invention is to provide a switch point roller assist apparatus which includes an adjustable clamp mechanism which can be frictionally secured on the main support structure to prevent the clamp plate from sliding off of the rail flange.
Another object of the present invention is to provide a switch point roller assist apparatus in which the rollers mounted on the roller support cage may be moved separately from the main support structure and may be adjusted after the switch point roller assist apparatus is installed on the rail.
Another object of the present invention is to provide a switch point roller assist apparatus which may be mounted on irregular rails and ties yet still provide assistance for movement of the point rails and operation of the switch.
Finally, an object of the present invention is to provide a switch point roller assist apparatus which is relatively simple and sturdy in construction and safe and efficient in use.